Radar detectors warn drivers of the use of police radar, and the potential for traffic law citations if the driver exceeds the speed limit. The FCC has allocated several regions of the electromagnetic spectrum for police radar use. The bands used by police radar are generally known as the X, K and Ka bands. Each relates to a different part of the spectrum. The X and K bands are relatively narrow frequency ranges, whereas the Ka band is a relatively wide range of frequencies. By the early 1990's, police radar evolved to the point that it could operate almost anywhere in the 1600-megahertz wide Ka band. During that time radar detectors kept pace with models that included descriptive names like “Ultra Wide” and “Super Wide.” More recently, police have begun to use laser (optical) systems for detecting speed. This technology was termed LIDAR for “LIght Detection And Ranging.”
Radar detectors typically comprise a microwave receiver and detection circuitry that is typically realized with a microprocessor or digital signal processor (DSP). Microwave receivers are generally capable of detecting microwave components in the X, K, and very broad Ka band. In various solutions, either a microprocessor or DSP is used to make decisions about the signal content from the microwave receiver. Systems including a digital signal processor have been shown to provide superior performance over solutions based on conventional microprocessors due to the DSP's ability to find and distinguish signals that are buried in noise. Various methods of applying DSP's were disclosed in U.S. Pat. Nos. 4,954,828, 5,079,553, 5,049,885, and 5,134,406, each of which is hereby incorporated by reference herein.
Police use of laser has also been countered with laser detectors, such as described in U.S. Pat. Nos. 5,206,500, 5,347,120 and 5,365,055, each of which is incorporated herein by reference. Products are now available that combined laser detection into a single product with a microwave receiver, to provide comprehensive protection.
The DSP or microprocessor in a modern radar detector is programmable. Accordingly, it can be instructed to manage all of the user interface features such as input switches, lights, sounds, as well as generate control and timing signals for the microwave receiver and/or laser detector. Early in the evolution of the radar detector, consumers sought products that offered a better way to manage the audible volume and duration of warning signals. Good examples of these solutions are found in U.S. Pat. Nos. 4,631,542, 5,164,729, 5,250,951, and 5,300,932, each of which is hereby incorporated by reference, which provide methods for conditioning the response generated by the radar detector.
Methods for conditioning detector response are gaining importance, because there are an increasing number of signals present in the X, K, and Ka bands from products that are completely unrelated to police radar. These products share the same regions of the spectrum and are also licensed by the FCC. The growing number of such signals is rapidly undermining the credibility of radar detector performance. Radar detectors cannot tell the difference between emissions from many of these devices and true police radar systems. As a result, radar detectors are increasingly generating false alarms, effectively “crying wolf”, reducing the significance of warnings from radar detectors. Among the possible sources of false alarms are microwave door openers, public safety systems such as ARTEMIS, and other radar detectors. At this time, there are very few signal sources that can cause false laser detections in comparison to the substantial list of false microwave signals just described. However certain locations near airports have been demonstrated to cause such problems for various laser detector products. The issue of false signals and ways of addressing geographically fixed false sources, is addressed in the above-referenced U.S. Pat. No. 6,670,905, in which the characteristics of false sources are stored with reference to the GPS-based location of the source, so that in subsequent encounters the false source may be ignored or the response to that source conditioned.
Vehicle electronics continue to increase in sophistication; GPS receivers and satellite receivers are now commonplace. Furthermore, wireless (typically Bluetooth) connectivity to cellular telephones and cellular networks has become commonplace, permitting hands free operation and in some circumstances, Internet or text messaging (SMS) connectivity within the vehicle electronic systems. As these vehicle electronic systems continue to propagate and increase in complexity, increasingly sophisticated functionality will be available to drivers from their vehicle electronics.